学进去

Serving Up Hope

Food allergies have been on the rise. In the US, it is now estimated that over 10 percent of the adult population has an allergy to peanuts, shellfish, dairy or another type of food. In the UK, the past three decades have seen hospital admissions for food allergies rise fivefold. Thankfully, we are building up the armory needed to reverse this trend so that, one day, such potentially deadly reactions become a thing of the past.

The most common types of food allergies are triggered by antibodies that we make called immunoglobulin (免疫球蛋白) E or IgE. These antibodies were discovered in the mid-1960s and kick-started an era of allergy research that is still going strong today. The early findings have spawned thousands of studies that paint an intricate (复杂的) picture of how allergies work, suggesting ways in which we can prevent and treat them.

When someone has a food allergy, IgE is involved in triggering a response when the immune system comes into contact with that food. Essentially, the body sees that part of your meal as an enemy, releasing histamine (组织胺) and other inflammatory chemicals in an attempt to deal with it. This causes symptoms ranging from itchiness and sneezes to wheezing (喘气) and anaphylactic shock (过敏性休克). The result can be anything from a mild inconvenience to death.

The old saying "prevention is better than the cure" holds true for food allergies. My colleagues and I use the so-called six Ds as a guide to preventative measures during childhood: diet, dirt, dogs, dry skin, detergents (清洁剂) and vitamin D. Studies have found that people have a lower risk of developing an allergy when, as youngsters, they eat a diverse diet and do so often, have healthy vitamin D levels, live in a home with a dog, avoid dry skin and are exposed to dirt, allowing them to develop a good microbiome (微生物组). The use of harsh detergents has also been associated with an increase in IgE.

Clearly, for many people that have food allergies, such early life prevention is no longer an option. However, other approaches are taking shape.

Most of the interventions we currently use target the immune system in an effort to retrain its response to allergens. One technique, known as allergen immunotherapy (免疫疗法), involves slowly building up exposure to a problem food. By starting in very small doses, the body appears to be able to be retrained to no longer see it as a threat. However, immunotherapy needs regular exposure to allergens, which can cause side effects.

Allergy vaccines are another option. These work by reshaping the body's immune response to a particular food so it doesn't end in illness.

As we gain evidence and experience with each of these approaches, we are moving closer to being able to treat all food allergies.